This project is built around a PCB graciously supplied to me by MikeW on these forums. This board is very well made with really good labeling for all components and connections!!
I wanted to keep this Aleph truely MINI so I went with just one pair of IRFP240 output devices, other parts are 1% mf Dale resistors, Panasonic electrolytic caps, and film type caps. A surplus but new Stancor P6434 filament trannny supplies 12.6 C.T. volts AC at close to 5A to the bridge developing around plus and minus 16 volts with one channel operating. A temporary pair of 27000@50 volts makes up the temporary filtration till smaller caps arrive. Heatsinks are fairly massive, but smaller versions, of the huge sinks I used on my 2's. and should suffice for convection cooling. With the chassis design I made up forced air coling would be a cinch if desired. A low RPM fan will blow air into the chassis rear and divert it to the bottom of each sink and then exit at the top.
Tommrrow I'll wire up the other channel and later this week post some photos and measurements of the unit.
Mark
SLC, UT
I wanted to keep this Aleph truely MINI so I went with just one pair of IRFP240 output devices, other parts are 1% mf Dale resistors, Panasonic electrolytic caps, and film type caps. A surplus but new Stancor P6434 filament trannny supplies 12.6 C.T. volts AC at close to 5A to the bridge developing around plus and minus 16 volts with one channel operating. A temporary pair of 27000@50 volts makes up the temporary filtration till smaller caps arrive. Heatsinks are fairly massive, but smaller versions, of the huge sinks I used on my 2's. and should suffice for convection cooling. With the chassis design I made up forced air coling would be a cinch if desired. A low RPM fan will blow air into the chassis rear and divert it to the bottom of each sink and then exit at the top.
Tommrrow I'll wire up the other channel and later this week post some photos and measurements of the unit.
Mark
SLC, UT
I've now got both channels up and running. Its a neato little amp for sure. The Stancor surplus tranny is running a bit on the hot side so I've ordered a custom tranny from Victoria Magnetics.
Initial listening impressions are that its somewhat neutral sounding and has alot of the sound traits of the Aleph 2. Unfortunately my digital camera was stolen so pictures will be another few days in comming.
BTW: The tranny will be 160 va, dual 12.6 volt (about 6 amp) secondaries. John Snowden says he can make this size tranny quite small in keeping with the theme of the Mini Aleph.
Mark
Initial listening impressions are that its somewhat neutral sounding and has alot of the sound traits of the Aleph 2. Unfortunately my digital camera was stolen so pictures will be another few days in comming.
BTW: The tranny will be 160 va, dual 12.6 volt (about 6 amp) secondaries. John Snowden says he can make this size tranny quite small in keeping with the theme of the Mini Aleph.
Mark
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